A function of a torque limiter for interrupting transmission of an excessive driving force is frequently required for a power transmission. For example, when a driving force from a vehicle engine is transmitted to a compressor used in an air conditioning system for a vehicle to drive the compressor, in case where the drive load of the compressor side as a driven body becomes excessive from some reason, it is required to interrupt transmission of the driving force (transmission of torque) in order to protect the vehicle engine or a belt.
Various mechanisms are known as such a mechanism for interrupting transmission of torque, and for example, known is a fracture-type torque limiter which is provided with a member or a section to be fractured when a transmission load over a predetermined value is applied between a member at the driving side and a member at the driven side. For example, in a power transmission disclosed in Patent document 1, a fracture-type torque limiter is provided wherein, when a compressor is abnormally stopped by a failure, etc., a coupling member which is provided between a pulley at the drive source side and a rotation transmission plate attached to a shaft of the compressor at the driven side is fractured.    Patent document 1: Japanese Utility Model 6-39105